Before I drywall this room I need help with a couple issues. I've been reading about subwoofer placement and I'm getting some conflicting info. The room in 12' x 26' with 8' ceilings. Left and front wall and floor are concrete. Speaker setup will be 7.1. Now, I've read the best sub lactions are 1) a corner, 2) 1/3 down the longest unbroken wall, 3)you have to "find" the best location. I need to prewire for this RG6 cable Box somewhere in this room. So what should I do? Reagarding the surround backs. I've studied the THX and Dolby speaker placemment diagrams and I'm lost. THX has you place both speakers directly behind in close proximity. Dolby has them a 150 degree angle max. What should I pre-wire for? Thanks.